rotating the depth image about lowest row in 3D

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I have a depth image which I want to rotated about a point to project the points in another plane which is at an angle t from the plane about the col axis so, [r2 c2]' = [ct st ; -st ct] [r c]' Should give me a rotation about angle t, with the column axis of the lowest row (479th row) as the pivot. Lets think about it as seeing the optical plane from one side and seeing only the row axis Now, the problem is that I can't have the same depth values once I rotate the image. I don't know how the depth values would change. Can someone help me figure this out.